I wish to send message to multiple computers (LAN network).
each computer in lab is running the server except one computer which is the client.
problem : once message has been sent to first computer , the client stops to send to other computers.

CLIENT :

Dim ip As String
Dim i As Integer
Dim serverStream As NetworkStream
Dim outStream As Byte()

Assuming that the packets are flowing ok to the first client without issue, then the issue is most likely caused by trying to re-use an open connection. You need to close the connection before continuing to the next client: